This invention concerns prosthetic sphincter devices and, more particularly, such devices of the kind comprising a closed pressure-fluid system operable by the recipient to control a body duct.
Prior devices of this kind can be seen to involve in common four basic component parts, namely, a reservoir for the pressure fluid, an inflatable duct-obturating means, a pump facility operable by the recipient to inflate and/or deflate the obturating means, and a control mechanism for the pump facility, interconnected by tubing. Typically the device is wholly implantable, the pump facility is located subcutaneously for operation by palpation, and the obturating means is a cuff locatable around the urethra or other appropriate site to act against urinary incontinence when inflated and to allow urination when deflated.
In an earlier form of these devices, the pump facility and control mechanism comprise separate pumps connected, by way of valves, between the reservoir and cuff respectively for inflation and deflation. The valves are essentially of unidirectional flow type to direct the pumped fluid appropriately, and also serve a pressure relief function to ensure that the cuff is not inflated above a preset pressure level.
In a subsequently developed form of the devices in question there is a single pump connected, by way of the control mechanism, between the reservoir and cuff to deflate the latter. In this case the reservoir serves to hold fluid at a preset pressure and the control mechanism allows a restricted flow to the cuff to maintain the same normally inflated at such pressure.
It will be appreciated that the devices available are not without certain disadvantages. They are frequently relatively complex, requiring a number of mechanical parts, all of which may be subject to mechanical failure or failure to function correctly.